Acoustic panels and methods for preparing them

ABSTRACT

The disclosure relates to acoustic panels and methods for preparing them. The disclosure relates more particularly to panels having a porous facing and to methods for making such panels. One aspect of the disclosure is an acoustic panel comprising a base structure. The base structure has one or more edges, an outward major surface having a total area, and an inward major surface opposing the outward major surface. The base structure has a noise reduction coefficient (NRC) of at least about 0.3. The panel includes a coating layer directly disposed on the outward major surface of the base structure, the coating layer being formed of an open-cell foam. The coating layer has an exterior major surface opposing the outward major surface of the base structure. The coating layer is substantially scattering for light in the wavelength range of 380 nm to 780 nm, and has an absorption coefficient of less than 0.5 for acoustic frequencies in the range of 100 Hz to 10,000 Hz.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/514,768, filed Jul. 16, 2019, which claims the benefit of priority ofU.S. Provisional Patent Application No. 62/699,570, filed Jul. 17, 2018,each of which is hereby incorporated herein by reference in itsentirety.

BACKGROUND OF THE DISCLOSURE Field of the Disclosure

The disclosure generally relates to acoustic panels and methods forpreparing them. The disclosure relates more particularly to panelshaving a porous coating layer and to methods for making such panels.

Description of Related Art

Acoustic panels are useful in a number of applications to attenuatenoise. For example, an interior ceiling structure can include a systemof sound absorbing panels installed on a metal grid. The grid issuspended below a structural ceiling of a room to create a plenum, orair space, between the rear surface of the panels and the ceiling. Thefront sides of the panels are viewed from below as a dropped ceiling ofthe room.

Acoustic panels suitable for a ceiling structure typically comprise alightweight material such as mineral wool, gypsum, fiberglass, woodfiber, paper, cellulose fiber, wet-laid felt, or foam. The panels can beperforated to achieve a desired acoustic absorbency. Perforating opensthe plane surface and the internal structure of the acoustic panel toallow air and sound waves to move in and out of the panel.

The physical features of conventional acoustic panels such as, forexample, porous fiberglass panels or perforated mineral wool panels, aretypically visible, for example, when viewed from below as part of adropped ceiling of a room. Conventional methods for obscuring thephysical features of acoustic panels involve laminating a facing ontothe panel, but such methods are limited, in large part because mostcoverings decrease the acoustic performance of the panel. Moreover,conventional facings are not cost-effective. For example, in the case ofa conventional glass mat facing for an acoustic panel, the facing isformed with an expensive formaldehyde-free binder, the laminationprocess is itself costly, and the weight and fragility of the panelsincreases after lamination.

Accordingly, there remains a need for a lightweight acoustic panelhaving an acoustically transparent coating layer, and for a simple,cost-effective method for preparing such panels.

SUMMARY OF THE DISCLOSURE

In one aspect, the present disclosure provides an acoustic panelcomprising:

-   -   a base structure having one or more edges, an outward major        surface having a total area, and an inward major surface        opposing the outward major surface, the base structure having        independently a noise reduction coefficient of at least about        0.3; and    -   a coating layer directly disposed on the outward major surface        of the base structure, the coating layer being formed of an        open-cell foam, the coating layer having an exterior major        surface opposing the outward major surface of the base        structure,    -   wherein the coating layer is substantially scattering for light        in the wavelength range 380-780 nm, and has an absorption        coefficient of less than 0.5 for acoustic frequencies in the        range of 100 Hz to 10,000 Hz.

In another aspect, the present disclosure provides a method forpreparing an acoustic panel according to the disclosure, comprising

-   -   providing a base structure having one or more edges, an outward        major surface having a total area, and an inward major surface        opposing the outward major surface, the base structure having        independently an NRC of at least about 0.3;    -   coating, directly onto the outward major surface, a frothed        composition comprising an aqueous suspension of one or more        foamable polymers (e.g., one or more of a rubber polymer and a        plastic polymer), and one or more of a dispersant, a coalescing        aid, and a foaming surfactant, present in the composition in a        combined amount of at least about 50%, e.g., at least about 60%,        or at least about 70%, or at least about 80%, or at least about        90%; and    -   drying the coated frothed composition to provide a coating layer        formed of an open-cell foam, the coating layer having an        exterior major surface opposing the outward major surface of the        base structure.

In another aspect, the present disclosure provides a panel systemcomprising

-   -   a plurality of support beams arranged in a support grid so as to        form a plurality of grid openings in the support grid; and    -   a plurality of panels respectively aligned with the openings of        the support grid, the plurality of panels including a first        acoustic panel according to claim 65, wherein the first acoustic        panel is oriented such that the exterior major surface of the        facing layer is facing an interior space adjacent to the support        grid.

Other aspects of the disclosure will be apparent to the person ofordinary skill in the art based on the drawings and detailed descriptionbelow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an image of an acoustic panel comprising a coating layeraccording to one embodiment of the disclosure.

FIG. 2 is a graph of impedance tube measurements of an uncoatedfiberglass substrate and of a coated fiberglass substrate following theprocedure of ASTM C384.

DETAILED DESCRIPTION OF THE DISCLOSURE

The particulars shown herein are by way of example and for purposes ofillustrative discussion of the preferred embodiments of the presentinvention only and are presented in the cause of providing what isbelieved to be the most useful and readily understood description of theprinciples and conceptual aspects of various embodiments of theinvention. In this regard, no attempt is made to show structural detailsof the invention in more detail than is necessary for the fundamentalunderstanding of the invention, the description taken with the drawingsand/or examples making apparent to those skilled in the art how theseveral forms of the invention may be embodied in practice. Thus, beforethe disclosed processes and devices are described, it is to beunderstood that the aspects described herein are not limited to specificembodiments, apparatuses, or configurations, and as such can, of course,vary. It is also to be understood that the terminology used herein isfor the purpose of describing particular aspects only and, unlessspecifically defined herein, is not intended to be limiting.

The terms “a,” “an,” “the” and similar referents used in the context ofdescribing the invention (especially in the context of the followingclaims) are to be construed to cover both the singular and the plural,unless otherwise indicated herein or clearly contradicted by context.Recitation of ranges of values herein is merely intended to serve as ashorthand method of referring individually to each separate valuefalling within the range. Unless otherwise indicated herein, eachindividual value is incorporated into the specification as if it wereindividually recited herein. Ranges can be expressed herein as from“about” one particular value, and/or to “about” another particularvalue. When such a range is expressed, another aspect includes from theone particular value and/or to the other particular value. Similarly,when values are expressed as approximations, by use of the antecedent“about,” it will be understood that the particular value forms anotheraspect. It will be further understood that the endpoints of each of theranges are significant both in relation to the other endpoint, andindependently of the other endpoint.

All methods described herein can be performed in any suitable order ofsteps unless otherwise indicated herein or otherwise clearlycontradicted by context. The use of any and all examples, or exemplarylanguage (e.g., “such as”) provided herein is intended merely to betterilluminate the invention and does not pose a limitation on the scope ofthe invention otherwise claimed. No language in the specification shouldbe construed as indicating any non-claimed element essential to thepractice of the invention.

Unless the context clearly requires otherwise, throughout thedescription and the claims, the words ‘comprise’, ‘comprising’, and thelike are to be construed in an inclusive sense as opposed to anexclusive or exhaustive sense; that is to say, in the sense of“including, but not limited to”. Words using the singular or pluralnumber also include the plural and singular number, respectively.Additionally, the words “herein,” “above,” and “below” and words ofsimilar import, when used in this application, shall refer to thisapplication as a whole and not to any particular portions of theapplication.

As will be understood by one of ordinary skill in the art, eachembodiment disclosed herein can comprise, consist essentially of orconsist of its particular stated element, step, ingredient or component.As used herein, the transition term “comprise” or “comprises” meansincludes, but is not limited to, and allows for the inclusion ofunspecified elements, steps, ingredients, or components, even in majoramounts. The transitional phrase “consisting of” excludes any element,step, ingredient or component not specified. The transition phrase“consisting essentially of” limits the scope of the embodiment to thespecified elements, steps, ingredients or components and to those thatdo not materially affect the embodiment.

Unless otherwise indicated, all numbers expressing quantities ofingredients, properties such as molecular weight, reaction conditions,and so forth used in the specification and claims are to be understoodas being modified in all instances by the term “about.” Accordingly,unless indicated to the contrary, the numerical parameters set forth inthe specification and attached claims are approximations that may varydepending upon the desired properties sought to be obtained by thepresent invention. At the very least, and not as an attempt to limit theapplication of the doctrine of equivalents to the scope of the claims,each numerical parameter should at least be construed in light of thenumber of reported significant digits and by applying ordinary roundingtechniques. When further clarity is required, the term “about” has themeaning reasonably ascribed to it by a person skilled in the art whenused in conjunction with a stated numerical value or range, i.e.,denoting somewhat more or somewhat less than the stated value or range,e.g., to within a range of ±20% of the stated value; ±19% of the statedvalue; ±18% of the stated value; ±17% of the stated value; ±16% of thestated value; ±15% of the stated value; ±14% of the stated value; ±13%of the stated value; ±12% of the stated value; ±11% of the stated value;±10% of the stated value; ±9% of the stated value; ±8% of the statedvalue; ±7% of the stated value; ±6% of the stated value; ±5% of thestated value; ±4% of the stated value; ±3% of the stated value; ±2% ofthe stated value; or ±1% of the stated value.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the invention are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contains certainerrors necessarily resulting from the standard deviation found in theirrespective testing measurements.

Groupings of alternative elements or embodiments of the inventiondisclosed herein are not to be construed as limitations. Each groupmember may be referred to and claimed individually or in any combinationwith other members of the group or other elements found herein. It isanticipated that one or more members of a group may be included in, ordeleted from, a group for reasons of convenience and/or patentability.When any such inclusion or deletion occurs, the specification is deemedto contain the group as modified thus fulfilling the written descriptionof all Markush groups used in the appended claims.

Some embodiments of this invention are described herein, including thebest mode known to the inventors for carrying out the invention. Ofcourse, variations on these described embodiments will become apparentto those of ordinary skill in the art upon reading the foregoingdescription. The inventor expects skilled artisans to employ suchvariations as appropriate, and the inventors intend for the invention tobe practiced otherwise than specifically described herein. Accordingly,this invention includes all modifications and equivalents of the subjectmatter recited in the claims appended hereto as permitted by applicablelaw. Moreover, any combination of the above-described elements in allpossible variations thereof is encompassed by the invention unlessotherwise indicated herein or otherwise clearly contradicted by context.

As the person of ordinary skill in the art will appreciate, directionssuch as “vertical,” “horizontal,” “upper” and “lower” are definedrelative to how the support member is to be installed, with the ceilingdefined as “up.”

Furthermore, numerous references have been made to patents and printedpublications throughout this specification. Each of the cited referencesand printed publications are individually incorporated herein byreference in their entirety.

In closing, it is to be understood that the embodiments of the inventiondisclosed herein are illustrative of the principles of the presentinvention. Other modifications that may be employed are within the scopeof the invention. Thus, by way of example, but not of limitation,alternative configurations of the present invention may be utilized inaccordance with the teachings herein. Accordingly, the present inventionis not limited to that precisely as shown and described.

In various aspects and embodiments, the disclosure relates to anacoustic panel having a coating layer. The disclosure demonstrates suchpanels to be relatively inexpensive and lightweight, and such coatinglayers to be acoustically transparent and obscuring of a base structure.One aspect of the disclosure is an acoustic panel comprising a basestructure. The base structure has one or more edges, an outward majorsurface having a total area, and an inward major surface opposing theoutward major surface. The base structure has independently a noisereduction coefficient (NRC) of at least about 0.3. The panel includes acoating layer directly disposed on the outward major surface of the basestructure, the coating layer being formed of an open-cell foam. Thecoating layer has an exterior major surface opposing the outward majorsurface of the base structure. The coating layer is substantiallyscattering for light in the wavelength range of 380 nm to 780 nm, andhas an absorption coefficient of less than 0.5 for acoustic frequenciesin the range of 100 Hz to 10,000 Hz.

The person of ordinary skill in the art will appreciate that an“absorption coefficient” of a panel may be determined throughstandardized testing procedures such as, for example, ASTM C423(“Standard Test Method for Sound Absorption and Sound AbsorptionCoefficients by the Reverberation Room Method”). The person of ordinaryskill in the art will further appreciate that, while intended todescribe the fraction of randomly incident sound power absorbed by asurface, an absorption coefficient is defined operationally, andaccordingly, highly absorptive panels can have an absorption coefficientexceeding unity at one or more frequencies. As used herein, a “noisereduction coefficient” or “NRC” describes the arithmetic average (e.g.,rounded to the nearest multiple of 0.05), of the absorption coefficientsfor a specific panel determined at 250 Hz, 500 Hz, 1000 Hz, and 2000 Hz.

One embodiment of the disclosure is shown in schematic view in FIG. 1 .A primary component of the panel 10 is a base structure 12. The basestructure 12 has an outward major surface 14, an inward major surface16, and edges 18. In certain embodiments as otherwise described herein,the base structure comprises one or more of mineral wool, fiberglass,gypsum, wood fiber, paper, cellulose fiber, wet-laid felt, and foam. Incertain such embodiments, the base structure comprises one or morefillers, and one or more binders. For example, in certain embodiments asotherwise described herein, the mineral wool, fiberglass, gypsum, woodfiber, paper, cellulose fiber, wet-laid felt, and/or foam, and the oneor more fillers and one or more binders are present in the basestructure in a combined amount of at least 85 wt. %, or at least about90 wt. %, or at least about 95 wt. %, or at least about 97.5%, or atleast about 99 wt. %, or at least about 99.5 wt. %. In certainembodiments as otherwise described herein, the base structure comprisesmineral wool. The person of ordinary skill in the art will appreciatethat a number of fillers suitable for a base structure (e.g., a basestructure comprising mineral wool) are known in the art. For example, incertain embodiments as otherwise described herein, the base structurecomprises one or more fillers selected from dolomite, wollastonite, sawdust, fly ash, recycled plastic, rubber crumb, gypsum, glass, perlite,wood pulp (i.e., cellulose), recycled paper, and recycled glass. Theperson of ordinary skill in the art will further appreciate that anumber of binders suitable for a base structure (e.g., a base structurecomprising mineral wool) are known in the art. For example, in certainembodiments as otherwise described herein, the base structure comprisesone or more binders selected from urea-formaldehyde resin, phenolicresin, polyurethane, polyacrylates, polystyrene, styrene-acrylatecopolymers, styrene-butadiene copolymers (i.e., styrene-butadienerubber, SBR), styrene-butadiene-styrene block copolymer (SBS),styrene-ethylene-butadiene-styrene block copolymer (SEBS), poly(vinylacetate) (PVAc), poly(vinyl alcohol) (PVA), poly(ethylene-vinyl acetate)(EVA), ethylene-vinyl chloride copolymers, silicones, nylons, acetals,polyethylene oxide, acrylic resins, and starches, e.g., modifiedstarches.

In certain embodiments as otherwise described herein, the outward majorsurface of the base structure comprises a localized pigment (e.g.,provided by applying a pigment to the outward major surface of the basestructure). In certain such embodiments, the color of the outward majorsurface is white.

In certain embodiments as otherwise described herein, the outward majorsurface of the base structure comprises a localized adhesive. However,the present inventors have determined that the acoustic panels asotherwise described herein can be prepared according to methods asotherwise described herein, without the use of a localized adhesive,which can be costly and can negatively affect the acoustic performanceof the panel. Accordingly, in certain embodiments, an adhesive is notlocalized on the outward major surface of the base structure of theacoustic panel as otherwise described herein. In certain suchembodiments, neither is a pigment localized on the outward major surfaceof the base structure.

In certain embodiments as otherwise described herein, the base structuredoes not comprise perforations. For example, in certain suchembodiments, the base structure has one or more physical properties(e.g., porosity) that provide desirable acoustic properties.

In other embodiments, the base structure comprises a plurality ofperforations extending from the outward major surface towards the inwardmajor surface, the plurality of perforations occupying an area of theoutward major surface. As used herein, the shape of a perforation at itsopening may be elongated (e.g., may have an aspect ratio of 2, or 3, or4, or 5, etc.), or may be annular (e.g., circular). In certainembodiments as otherwise described herein, the perforations have anaverage depth of less than about 4 mm. For example, in certain suchembodiments, the perforations have an average depth within the range ofabout 2 mm to about 4 mm. In other embodiments, the perforations have anaverage depth of at least about 4 mm. For example, in certain suchembodiments, the perforations have an average depth within the range ofabout 4 mm to about 12 mm. The person of ordinary skill in the art willappreciate that, in some aspects, perforations as used herein, having anelongated opening and an average depth of less than about 4 mm are alsoknown in the art as “fissures.”

Base structure 12 comprises a plurality of perforations 20 (shown inpart in FIG. 1 ). In certain embodiments as otherwise described herein,the plurality of perforations occupies an area of the outward majorsurface that is within the range of about 0.1% to about 10% of the totalarea of the outward major surface of base structure 12. For example, incertain embodiments as otherwise described herein, the perforationsoccupy an area of the outward major surface within the range of about0.1% to about 9%, or about 0.1% to about 8%, or about 0.1% to about 7%,or about 0.1% to about 6%, or about 0.1% to about 5%, or about 0.1% toabout 4%, or about 0.25% to about 10%, or about 0.5% to about 10%, orabout 0.75% to about 10%, or about 1% to about 10%, or about 1.5% toabout 10%, or about 2% to about 10%, or about 2.5% to about 10%, orabout 3% to about 10%, or about 4% to about 10%, or about 5% to about10%, or about 6% to about 10%, or about 7% to about 10%, or about 0.25%to about 9%, or about 0.5% to about 8%, or about 0.75% to about 7%, orabout 1% to about 6%, or about 1.5% to about 5% of the total area of theoutward major surface.

In certain embodiments as otherwise described herein, the perforationshave an average depth of at least about 4 mm, such as an average depthwithin the range of about 4 mm to about 12 mm, or about 5 mm to about 10mm. In certain embodiments as otherwise described herein, the pluralityof perforations are annular, and the perforations have an averagediameter within the range of about 0.25 mm to about 5 mm. For example,in certain such embodiments, the average diameter of the perforations iswithin the range of about 0.25 mm to about 4.5 mm, or about 0.25 mm toabout 4 mm, or about 0.25 mm to about 3.5 mm, or about 0.25 mm to about3 mm, or about 0.25 mm to about 2.5 mm, or about 0.25 mm to about 2 mm,or about 0.25 mm to about 1.5 mm, or about 0.5 mm to about 5 mm, orabout 0.75 mm to about 5 mm, or about 1 mm to about 5 mm, or about 1.25mm to about 5 mm, or about 1.5 mm to about 5 mm, or about 2 mm to about5 mm, or about 2.5 mm to about 5 mm, or about 3 mm to about 5 mm, orabout 3.5 mm to about 5 mm, or about 0.5 mm to about 4 mm, or about 0.5mm to about 3.5 mm, or about 0.5 mm to about 3 mm, or about 0.75 mm toabout 2.5 mm, or about 1 mm to about 2.5 mm.

Base structure 12 has a thickness 22. In certain embodiments asotherwise described herein, the base structure has a thickness withinthe range of about 2 mm to about 50 mm. For example, in certain suchembodiments, the thickness of the base structure is within the range ofabout 2 mm to about 45 mm, or about 2 mm to about 40 mm, or about 2 mmto about 35 mm, or about 2 mm to about 30 mm, or about 2 mm to about 25mm, or about 2 mm to about 20 mm, or about 2 mm to about 17.5 mm, orabout 2 mm to about 15 mm, or about 2 mm to about 10 mm, or about 3 mmto about 50 mm, or about 4 mm to about 50 mm, or about 5 mm to about 50mm, or about 6 mm to about 50 mm, or about 7 mm to about 50 mm, or about8 mm to about 50 mm, or about 9 mm to about 50 mm, or about 10 mm toabout 50 mm, or about 12.5 mm to about 50 mm, or about 15 mm to about 50mm, or about 17.5 mm to about 50 mm, or about 20 mm to about 50 mm, orabout 3 mm to about 45 mm, or about 3 mm to about 40 mm, or about 4 mmto about 35 mm, or about 5 mm to about 30 mm, or about 5 mm to about 25mm, or about 5 mm to about 20 mm.

In certain embodiments as otherwise described herein, a width of theacoustic panel is within the range of about 12 to about 60 inches, e.g.,from 23 to 25 inches or from 46 to 50 inches, and a length of theacoustic panel is within the range of about 12 to about 144 inches,e.g., from 23 to 25 inches or from 46 to 50 inches.

The person of ordinary skill in the art will appreciate that basestructure 12 will have certain acoustic properties. In some aspects,base structure 12 has a characteristic noise reduction coefficient (NRC)of at least about 0.3. In certain embodiments as otherwise describedherein, the base structure has independently a noise reductioncoefficient of at least about 0.5. For example, in certain embodimentsas otherwise described herein, the base structure has independently anoise reduction coefficient of at least about 0.55, or at least about0.6, or at least about 0.65, or at least about 0.7, or at least about0.75, or at least about 0.8, or at least about 0.85, or at least about0.9, or at least about 0.95.

Panel 10 further includes a coating layer 24 directly disposed on theoutward major surface of the base structure, the coating layer having anexterior major surface 26 opposing the outward major surface of the basestructure. The coating layer 24 is formed of an open-cell foam.

Coating layer 24 has, independently of the base structure, acharacteristic sound absorption coefficient. As noted above, the coatinglayer of the acoustic panel as otherwise described herein has anabsorption coefficient of less than 0.5 for acoustic frequencies in therange of 100 Hz to 10,000 Hz. In certain embodiments as otherwisedescribed herein, the coating layer has an absorption coefficient ofless than 0.45, or less than 0.4, or less than 0.35, or less than 0.3,or less than 0.25 for acoustic frequencies in the range of 100 Hz to10,000 Hz. In another example, in certain embodiments as otherwisedescribed herein, the coating layer and the base structure eachindependently have an air resistivity, and the air resistivity of thecoating layer is equal to or less than the air resistivity of the basestructure. In certain such embodiments, the air resistivity of the basestructure is at least 25%, or at least 50%, or at least 75%, or at leastabout 100% greater than the air resistivity of the coating layer. Insome embodiments, the air resistivity of the coating layer is in a rangeof about 1 to about 2000 kPa·s/m², or about 10 to about 1000 kPa·s/m²,or about 100 to about 500 kPa·s/m².

Additionally, coating layer 24 has a characteristic light scatteringpercentage. As noted above, the coating layer of the acoustic panel asotherwise described herein is substantially scattering for light in thewavelength range of 380 nm to 780 nm. In certain embodiments asotherwise described herein, the coating layer is substantiallyscattering for light in the wavelength range of 380 nm to 780 nm. Forexample, in certain such embodiments, the coating layer has a lightscattering percentage of at least about 50%, or at least about 55%, orat least about 60%, or at least about 65%, or at least about 70%, or atleast about 75%, or at least about 80%, or at least about 85%, or atleast about 90%, or at least about 95%, for a wavelength region of 380nm to 780 nm.

The person of ordinary skill in the art will further appreciate thatpanel 10, comprising base structure 12 and coating layer 24, will havecertain acoustic properties. In some aspects, panel 10 can have acharacteristic noise reduction coefficient. In certain embodiments asotherwise described herein, the acoustic panel has a noise reductioncoefficient of at least about 0.3. For example, in certain embodimentsas otherwise described herein, the acoustic panel has a noise reductioncoefficient of at least about 0.35, or at least about 0.4, or at leastabout 0.45. And in certain additional embodiments as otherwise describedherein, the acoustic panel has a noise reduction coefficient of at leastabout 0.55, or at least about 0.6, or at least about 0.65, or at leastabout 0.7, or at least about 0.75, or at least about 0.8, or at leastabout 0.85, or at least about 0.9, or at least about 0.95. In certainembodiments as otherwise described herein, the noise reductioncoefficient of the acoustic panel is at least about 70% of the noisereduction coefficient of the base structure independently. For example,in certain such embodiments, the noise reduction coefficient of theacoustic panel is at least about 75%, or at least about 80%, or at leastabout 85%, or at least about 90%, or at least about 95% of the noisereduction coefficient of the base structure independently.

Coating layer 24 has a thickness 28. In certain embodiments as otherwisedescribed herein, the thickness of the coating layer is within the rangeof about 0.1 mm to about 10 mm. For example, in certain suchembodiments, the thickness of the coating layer is within the range ofabout 0.1 mm to about 9 mm, or about 0.1 mm to about 8 mm, or about 0.1mm to about 7 mm, or about 0.1 mm to about 6 mm, or about 0.1 mm toabout 6 mm, or about 0.1 mm to about 5 mm, or about 0.1 mm to about 4mm, or about 0.25 mm to about 10 mm, or about 0.25 mm to about 10 mm, orabout 0.5 mm to about 10 mm, or about 0.75 mm to about 10 mm, or about 1mm to about 10 mm, or about 1.5 mm to about 10 mm, or about 2 mm toabout 10 mm, or about 3 mm to about 10 mm, or about 4 mm to about 10 mm,or about 5 mm to about 10 mm, or about 6 mm to about 10 mm, or about0.25 mm to about 9 mm, or about 0.25 mm to about 8 mm, or about 0.25 mmto about 7 mm, or about 0.25 mm to about 6 mm, or about 0.5 mm to about5 mm, or about 0.5 mm to about 4 mm.

As noted above, coating layer 24 is formed of an open-cell foam. Incertain aspects, the open-cell foam comprises a porous structure. Forexample, in certain embodiments as otherwise described herein, thecoating layer has an average cell diameter within the range of about 10μm to about 500 μm. In certain such embodiments, the coating layer hasan average cell diameter within the range of about 10 μm to about 450μm, or about 10 μm to about 400 μm, or about 10 μm to about 350 μm, orabout 10 μm to about 300 μm, or about 10 μm to about 250 μm, or about 10μm to about 200 μm, or about 25 μm to about 500 μm, or about 50 μm toabout 500 μm, or about 75 μm to about 500 μm, or about 100 μm to about500 μm, or about 150 μm to about 500 μm, or about 200 μm to about 500μm, or about 250 μm to about 500 μm, or about 300 μm to about 500 μm, orabout 25 μm to about 450 μm, or about 50 μm to about 400 μm, or about 75μm to about 350 μm, or about 100 μm to about 300 μm.

In certain embodiments as otherwise described herein, the coating layerhas a density within the range of about 0.01 g/cm³ to about 0.5 g/cm³,or about 0.01 g/cm³ to about 0.35 g/cm³, or about 0.01 g/cm³ to about0.25 g/cm³, or about 0.01 g/cm³ to about 0.15 g/cm³, or about 0.05 g/cm³to about 0.5 g/cm³, or about 0.1 g/cm³ to about 0.5 g/cm³, or about 0.2g/cm³ to about 0.5 g/cm³, or about 0.05 g/cm³ to about 0.35 g/cm³, orabout 0.05 g/cm³ to about 0.25 g/cm³, or about 0.1 g/cm³ to about 0.2g/cm³.

In certain embodiments as otherwise described herein, the coating layercomprises one or more foamable polymers (e.g., one or more of a rubberpolymer and a plastic polymer), and one or more of a dispersant, acoalescing aid, and a foaming surfactant, present in the layer in acombined amount of at least about 30 wt. %. For example, in certainembodiments as otherwise described herein, the one or more foamablepolymers, and the one or more of a dispersant, a coalescing aid, and afoaming surfactant are present in the layer in a combined amount of atleast about 35 wt. %, or at least about 40 wt. %, or at least about 45wt. %, or at least about 50 wt. %, or at least about 55 wt. %, or atleast about 60 wt. %, or at least about 65 wt. %, or at least about 70wt. %, or at least about 75 wt. %, or at least about 80 wt. %.

A foamable polymer can be used to provide the foamed structure of thecoating layer. A variety of polymers can be used, such as rubberpolymers and plastic polymers. In certain embodiments as otherwisedescribed herein, the coating layer comprises a rubber polymer. Forexample, in certain such embodiments, the rubber polymer of the coatinglayer is a styrene butadiene copolymer (e.g., styrene-butadiene rubber(SBR) and styrene-butadiene-styrene block copolymer (SBS)). In certainembodiments as otherwise described herein, the coating layer comprises aplastic polymer. For example, in certain such embodiments, the plasticpolymer of the coating layer is a polyacrylate such as poly(methylmethacrylate), poly(ethyl acrylate), poly(butyl acrylate), poly(acrylicacid), polystyrene, poly vinyl acetate or poly vinyl alcohol. Otherpolymers for use as foamable polymers include polyurethanes,polyacrylates, styrene-acrylate copolymers,styrene-ethylene-butadiene-styrene block copolymer (SEBS), poly(vinylacetate) (PVAc), poly(ethylene-vinyl acetate) (EVA), ethylene-vinylchloride copolymers. In many embodiments, the foamable polymer can beprovided as a latex (e.g., latex rubbers or acrylic latexes), having asolids content, e.g., of 30-70 wt % or 40-60 wt %, and an averageparticle size, e.g., of 50-500 nm. Examples include Rhoplex SG30 fromDow, Avicor 384 from Celanese, Sunbond 3410 from Omnova, and AcronolEdge 4750 from BASF. The acrylic latex emulsions are often a copolymermixture of polymethyl methacrylate, polybutyl acrylate, and polyethylacrylate with other additives. In certain embodiments, the polymer ofthe latex has a glass transition temperature below 70° C. A combinationof polymers can be used in order to provide the liquid composition usedto form the coating with a desired rheology, e.g., acrylic latextogether with an acrylic polymer. An example of a polymer that can beused to modify coating rheology is ACRYSOL™ ASE-60, an acid containing,acrylic emulsion copolymer available from Dow.

The person of ordinary skill in the art will appreciate that a number ofdispersants suitable for the coating layer, such as amphiphilic and/orionic compounds, are known in the art. In certain embodiments asotherwise described herein, the coating layer comprises a coalescingaid. The person of ordinary skill in the art will appreciate that anumber of coalescing aids suitable for the coating layer are known inthe art. For example, in certain such embodiments, the coalescing aid isselected from texanol (i.e., 2,2,4-trimethyl-1,3-pentanediolmonoisobutyrate), ethylene glycol phenyl ether, butyl cellosolve, butylcarbitol, benzoic acid isononyl ester, and organic solvent. In certainembodiments as otherwise described herein, the coating layer comprises afoaming surfactant. The person of ordinary skill in the art willappreciate that a number of foaming surfactants suitable for the coatinglayer are known in the art. For example, in certain such embodiments,the foaming surfactant is selected from triton X-100, sodium laurylether sulfate, sodium lauryl sulfate, ammonium lauryl sulfate, sodiumpareth sulfate, diethanolamine, oleic acid, cetyl betaine, sodium olefinsulfonate, ammonium stearate, sodium and ammonium sulfosuccinamides andsodium and ammonium sulfosuccinates.

In certain embodiments as otherwise described herein, the coating layerfurther comprises a filler. For example, in certain such embodiments,the filler is calcium carbonate. The person of ordinary skill in the artwill appreciate that a number of fillers suitable for the coating layer,such as silica, alumina, aluminum trihydrate, titanium oxide, zincoxide, magnesium oxide, barium sulfate, clay, mica, talc, kaolin,nepheline syenite, perlite, and glass. In certain embodiments asotherwise described herein, the filler is present in the coating layerin an amount within the range of about 1 wt. % to about 60 wt. %. Forexample, in certain such embodiments, the filler is present in thecoating layer in an amount within the range of about 1 wt. % to about 55wt. %, or about 1 wt. % to about 50 wt. %, or about 1 wt. % to about 45wt. %, or about 1 wt. % to about 40 wt. %, or about 1 wt. % to about 35wt. %, or about 1 wt. % to about 30 wt. %, or about 5 wt. % to about 60wt. %, or about 10 wt. % to about 60 wt. %, or about 15 wt. % to about60 wt. %, or about 20 wt. % to about 60 wt. %, or about 25 wt. % toabout 60 wt. %, or about 30 wt. % to about 60 wt. %, or about 5 wt. % toabout 55 wt. %, or about 10 wt. % to about 55 wt. %, or about 15 wt. %to about 50 wt. %, or about 20 wt. % to about 50 wt. %.

In certain embodiments as otherwise described herein, the coating layerfurther comprises a pigment. For example, in certain such embodiments,the pigment is titanium dioxide, zinc oxide, or carbon black. Othercommon pigments suitable in the sprayable mixture include, for example,transition metal and metal oxide pigments (e.g., iron oxides),anthraquinoids, quinacridone, phthalocyanines, ultramarines, nephelinesyenite, barium sulfate, aluminum trihydrate, and magnesium oxide. Incertain embodiments as otherwise described herein, the filler is presentin the coating layer in an amount within the range of about 0.5 wt. % toabout 20 wt. %. For example, in certain such embodiments, the filler ispresent in the coating layer in an amount within the range of about 0.5wt. % to about 17.5 wt. %, or about 0.5 wt. % to about 15 wt. %, orabout 0.5 wt. % to about 12.5 wt. %, or about 0.5 wt. % to about 10 wt.%, or about 0.5 wt. % to about 7.5 wt. %, or about 0.5 wt. % to about 5wt. %, or about 1 wt. % to about 20 wt. %, or about 1.5 wt. % to about20 wt. %, or about 2 wt. % to about 20 wt. %, or about 2.5 wt. % toabout 20 wt. %, or about 5 wt. % to about 20 wt. %, or about 7.5 wt. %to about 20 wt. %, or about 10 wt. % to about 20 wt. %, or about 12.5wt. % to about 20 wt. %, or about 15 wt. % to about 20 wt. %, or about 1wt. % to about 17.5 wt. %, or about 2.5 wt. % to about 15 wt. %, orabout 5 wt. % to about 12.5 wt. %.

A variety of other components can be present in the coating layer. Forexample, in certain embodiments, and depending on the particularfoamable polymer used, a crosslinking agent (or, a reaction productthereof with the foamable polymer) is present in the coating layer,e.g., in an amount in the range of 0.1 wt % to 15 wt %. A variety ofcrosslinking agents can be used, e.g., carbodiimide (such as CarbodiliteXV-02 from Nisshinbo Chemical), sulfur, zinc oxide, zincdithiocarbamate, mercaptobenzothiazole, ammonium zirconium carbonate,potassium zirconium carbonate and melamine-formaldehyde resin. Theperson of ordinary skill in the art will select an appropriatecrosslinking agent depending on the other components of the coatinglayer.

For example, in certain embodiments as otherwise described herein, thecoating layer formed of an open-cell foam comprises an acrylic polymer,styrene butadiene polymer, or a mixture thereof, present in the coatinglayer in an amount within the range of about 20 wt. % to about 80 wt. %(e.g., about 25 wt. % to about 70 wt. %, or about 30 wt. % to about 60wt. %). In certain such embodiments, the coating layer further comprisesa dispersant, present in the coating layer in an amount within the rangeof about 0.1 wt. % to about 10 wt. % (e.g., about 0.5 wt. % to about 8wt. %). In certain such embodiments, the coating layer further comprisesa coalescing aid, present in the coating layer in an amount within therange of about 0.1 wt. % to about 10 wt. % (e.g., about 0.5 wt. % toabout 8 wt. %). In certain such embodiments, the coating layer furthercomprises a foaming surfactant, present in the coating layer in anamount within the range of about 0.25 wt. % to about 25 wt. % (e.g.,about 0.25 wt % to about 15 wt %, or about 1 wt. % to about 12 wt. %).In certain such embodiments, the coating layer further comprises afiller (e.g., calcium chloride), present in the foam in an amount withinthe range of about 1 wt. % to about 60 wt. % (e.g., about 15 wt. % toabout 45 wt. %). In certain such embodiments, the coating layer furthercomprises a pigment, present in the foam in an amount within the rangeof about 0.5 wt. % to about 20 wt. % (e.g., about 2.5 wt. % to about 15wt. %).

In certain embodiments, as otherwise described herein, the coating layercomprises a plurality of particles (e.g., as a filler and/or as apigment). For example, in certain such embodiments, the coating layercomprises particles selected from rubber, plastic, glass, metal,ceramic, or mineral. In certain embodiments as otherwise describedherein, the particles are glass fibers, plastic fibers such aspolyester, polypropylene, polyethylene, polyethylene terephthalate,polyvinyl chloride, and polyamide fibers, and mineral fibers. In certainembodiments as otherwise described herein, the plurality of particleshas an average particle size within the range of about 1 nm to about 200nm (e.g., wollastonite particles having a size of about 8 nm) In certainembodiments as otherwise described herein, the plurality of particleshas an average particle size (i.e., the major dimension of a particle,or the length of a fiber) within the range of about 1 μm to about 50 μm.For example, in certain such embodiments, the plurality of particles hasan average particle size within the range of about 1 μm to about 40 μm,or about 1 μm to about 30 μm, or about 1 μm to about 20 μm, or about 5μm to about 50 μm, or about 10 μm to about 50 μm, or about 20 μm toabout 50 μm, or about 30 μm to about 50 μm, or about 5 μm to about 40μm, or about 5 μm to about 30 μm. In other embodiments as otherwisedescribed herein, the plurality of particles has an average particlesize within the range of about 0.1 mm to about 10 mm. For example, incertain such embodiments, the plurality of particles has an averageparticle size within the range of about 0.1 mm to about 8 mm, or about0.1 mm to about 6 mm, or about 0.1 mm to about 4 mm, or about 0.5 mm toabout 10 mm, or about 1 mm to about 10 mm, or about 2 mm to about 10 mm,or about 4 mm to about 10 mm, or about 0.5 mm to about 8 mm, or about0.5 mm to about 6 mm.

In certain embodiments as otherwise described herein, the total amountof the foamable polymer (e.g., rubber polymer and/or plastic polymer),dispersant, coalescing aid, foaming surfactant, filler, pigment, andcrosslinking agent is at least about 85 wt. % of the coating layer. Forexample, in certain such embodiments, the total amount of the foamablepolymer (e.g., rubber polymer and/or plastic polymer), dispersant,coalescing aid, foaming surfactant, filler, pigment, and crosslinkingagent is at least about 90 wt. %, or at least about 95 wt. %, or atleast about 97.5 wt. %, or at least about 99 wt. %, or at least about99.5 wt. % of the coating layer.

In certain embodiments as otherwise described herein, the exterior majorsurface of the coating layer comprises a localized pigment (e.g.,provided by applying a pigment to the exterior major surface of thecoating layer). In certain such embodiments, the color of the exteriormajor surface is white.

In certain embodiments, the exterior major surface of the coating layeris rough. For example, in certain such embodiments, the exterior majorsurface of the coating layer has a gloss of less than about 20 glossunits (GU) for gloss angles in the range of 20-85 degrees. For example,in certain embodiments as otherwise described herein, the exterior majorsurface of the coating layer has a gloss of less than about 17.5 GU, orless than about 15 GU, or less than about 12.5 GU, or less than about 10GU for gloss angles in the range of 20-85 degrees. In certain desirableembodiments, the exterior major surface of the coating layer has a glossof less than 7 GU, e.g., less than 5 GU or even less than 3 GU for glossangles in the range of 20-85 degrees.

In certain embodiments as otherwise described herein, the panel isresistant to sagging.

Another aspect of the disclosure is a method of preparing an acousticpanel. The disclosure demonstrates such methods to efficiently providerelatively inexpensive and lightweight acoustic panels having a coatinglayer that is transparent to sound and obscuring of a perforated basestructure. The method comprises providing a base structure having one ormore edges, an outward major surface having a total area, and an inwardmajor surface opposing the outward major surface. The base structure hasindependently a noise reduction coefficient (NRC) of at least about 0.3.The method includes coating, directly onto the outward major surface, afrothed composition comprising an aqueous suspension of foamable polymer(e.g., one or more of a rubber polymer and a plastic polymer), and oneor more of a dispersant, a coalescing aid, and a foaming surfactant,present in the composition in a combined amount of at least about 50%.The method includes drying the coated frothed composition to provide acoating layer formed of an open-cell foam, the coating layer having anexterior major surface opposing the outward major surface of the basestructure. The inventors have determined that the method provides arelatively lightweight coating layer without requiring separate coatinglayer formation and lamination steps. The amounts and identities of thevarious components of the base structure, including perforations, can beas otherwise described above with respect to the acoustic panels of thedisclosure.

In certain embodiments as otherwise described herein, the frothedcomposition has a density within the range of about 0.01 g/cm³ to about0.5 g/cm³, or about 0.01 g/cm³ to about 0.35 g/cm³, or about 0.01 g/cm³to about 0.25 g/cm³, or about 0.01 g/cm³ to about 0.15 g/cm³, or about0.05 g/cm³ to about 0.5 g/cm³, or about 0.1 g/cm³ to about 0.5 g/cm³, orabout 0.2 g/cm³ to about 0.5 g/cm³, or about 0.05 g/cm³ to about 0.35g/cm³, or about 0.05 g/cm³ to about 0.25 g/cm³, or about 0.1 g/cm³ toabout 0.2 g/cm³.

In certain embodiments as otherwise described herein, the frothedcomposition comprises a rubber polymer. For example, in certain suchembodiments, the rubber polymer is a styrene butadiene copolymer. Incertain embodiments as otherwise described herein, the frothedcomposition comprises a plastic polymer. For example, in certain suchembodiments, the plastic polymer is an polyacrylate such as poly(methylmethacrylate), poly(ethyl acrylate), poly(butyl acrylate), poly(acrylicacid), polystyrene, poly vinyl acetate or poly vinyl alcohol. Otherpolymers for use as foamable polymers include polyurethanes,polyacrylates, styrene-acrylate copolymers,styrene-ethylene-butadiene-styrene block copolymer (SEBS), poly(vinylacetate) (PVAc), poly(ethylene-vinyl acetate) (EVA), ethylene-vinylchloride copolymers. In many embodiments, the foamable polymer can beprovided as a latex (e.g., latex rubbers or acrylic latexes), having asolids content, e.g., of 30-70 wt % or 40-60 wt %, and an averageparticle size, e.g., of 50-500 nm. Examples include Rhoplex SG30 fromDow, Avicor 384 from Celanese, Sunbond 3410 from Omnova, and AcronolEdge 4750 from BASF. The acrylic latex emulsions are often a copolymermixture of polymethyl methacrylate, polybutyl acrylate, and polyethylacrylate with other additives. In certain embodiments, the polymer ofthe latex has a glass transition temperature below 70° C. A combinationof polymers can be used in order to provide the liquid composition usedto form the coating with a desired rheology, e.g., acrylic latextogether with an acrylic polymer. An example of a polymer that can beused to modify coating rheology is ACRYSOL™ ASE-60, an acid containing,acrylic emulsion copolymer available from Dow.

In certain embodiments as otherwise described herein, the frothedcomposition comprises a dispersant. The person of ordinary skill in theart will appreciate that a number of dispersants suitable for thefrothed composition, such as amphiphilic and/or ionic compounds, areknown in the art. In certain embodiments as otherwise described herein,the frothed composition comprises a coalescing aid. The person ofordinary skill in the art will appreciate that a number of coalescingaids suitable for the frothed composition are known in the art. Forexample, in certain such embodiments, the coalescing aid is selectedfrom texanol (i.e., 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate),ethylene glycol phenyl ether, butyl cellosolve, butyl carbitol, benzoicacid isononyl ester, and organic solvent. In certain embodiments asotherwise described herein, the frothed composition comprises a foamingsurfactant. The person of ordinary skill in the art will appreciate thata number of foaming surfactants suitable for the frothed composition areknown in the art. For example, in certain such embodiments, the foamingsurfactant is selected from triton X-100, sodium lauryl ether sulfate,sodium lauryl sulfate, ammonium lauryl sulfate, and sodium parethsulfate, ammonium stearate, sodium and ammonium sulfosuccinamides andsodium and ammonium sulfosuccinates.

In certain embodiments as otherwise described herein, the frothedcomposition further comprises a filler. For example, in certain suchembodiments, the filler is calcium carbonate. The person of ordinaryskill in the art will appreciate that a number of fillers suitable forthe frothed composition, such as silica, alumina, aluminum trihydrate,titanium oxide, zinc oxide, magnesium oxide, barium sulfate, clay, mica,talc, kaolin, nepheline syenite, perlite, and glass. In certainembodiments as otherwise described herein, the filler is present in thefrothed composition in an amount within the range of about 5 wt. % toabout 50 wt. %. For example, in certain such embodiments, the filler ispresent in the frothed composition in an amount within the range ofabout 5 wt. % to about 45 wt. %, or about 5 wt. % to about 40 wt. %, orabout 5 wt. % to about 35 wt. %, or about 5 wt. % to about 30 wt. %, orabout 5 wt. % to about 25 wt. %, or about 10 wt. % to about 50 wt. %, orabout 15 wt. % to about 50 wt. %, or about 20 wt. % to about 50 wt. %,or about 25 wt. % to about 50 wt. %, or about 30 wt. % to about 50 wt.%, or about 10 wt. % to about 45 wt. %, or about 10 wt. % to about 40wt. %, or about 15 wt. % to about 35 wt. %, or about 15 wt. % to about30 wt. %.

In certain embodiments as otherwise described herein, the frothedcomposition further comprises a pigment. For example, in certain suchembodiments, the pigment is titanium dioxide, zinc oxide, or carbonblack. Other common pigments suitable in the sprayable mixture include,for example, transition metal and metal oxide pigments (e.g., ironoxides), anthraquinoids, quinacridone, phthalocyanines, ultramarines,nepheline syenite, barium sulfate, aluminum trihydrate, and magnesiumoxide. In certain embodiments as otherwise described herein, the pigmentis present in the frothed composition in an amount within the range ofabout 0.5 wt. % to about 20 wt. %. For example, in certain suchembodiments, the pigment is present in the frothed composition in anamount within the range of about 0.5 wt. % to about 17.5 wt. %, or about0.5 wt. % to about 15 wt. %, or about 0.5 wt. % to about 12.5 wt. %, orabout 0.5 wt. % to about 10 wt. %, or about 0.5 wt. % to about 7.5 wt.%, or about 0.5 wt. % to about 5 wt. %, or about 1 wt. % to about 20 wt.%, or about 1.5 wt. % to about 20 wt. %, or about 2 wt. % to about 20wt. %, or about 2.5 wt. % to about 20 wt. %, or about 5 wt. % to about20 wt. %, or about 7.5 wt. % to about 20 wt. %, or about 10 wt. % toabout 20 wt. %, or about 12.5 wt. % to about 20 wt. %, or about 15 wt. %to about 20 wt. %, or about 1 wt. % to about 17.5 wt. %, or about 2.5wt. % to about 15 wt. %, or about 5 wt. % to about 12.5 wt. %.

The frothed composition can further include a crosslinker, as describedabove with respect to the coating layer. For example, in certainembodiments, and depending on the particular foamable polymer used, acrosslinking agent (or, a reaction product thereof with the foamablepolymer) is present in the coating layer, e.g., in an amount in therange of 0.1 wt % to 15 wt %. A variety of crosslinking agents can beused, e.g., carbodiimide (such as Carbodilite XV-02 from NisshinboChemical), sulfur, zinc oxide, zinc dithiocarbamate,mercaptobenzothiazole, ammonium zirconium carbonate, potassium zirconiumcarbonate and melamine-formaldehyde resin. The person of ordinary skillin the art will select an appropriate crosslinking agent depending onthe other components of the formulation.

In certain embodiments as otherwise described herein, the frothedcomposition comprises a plurality of particles (e.g., as filler and/orpigment). For example, in certain such embodiments, the frothedcomposition comprises particles selected from rubber, plastic, glass,metal, ceramic, or mineral. In certain embodiments as otherwisedescribed herein, the plurality of particles has an average particlesize within the range of about 1 μm to about 50 μm. For example, incertain such embodiments, the plurality of particles has an averageparticle size within the range of about 1 μm to about 40 μm, or about 1μm to about 30 μm, or about 1 μm to about 20 μm, or about 5 μm to about50 μm, or about 10 μm to about 50 μm, or about 20 μm to about 50 μm, orabout 30 μm to about 50 μm, or about 5 μm to about 40 μm, or about 5 μmto about 30 μm. In other embodiments as otherwise described herein, theplurality of particles has an average particle size within the range ofabout 0.1 mm to about 10 mm. For example, in certain such embodiments,the plurality of particles has an average particle size within the rangeof about 0.1 mm to about 8 mm, or about 0.1 mm to about 6 mm, or about0.1 mm to about 4 mm, or about 0.5 mm to about 10 mm, or about 1 mm toabout 10 mm, or about 2 mm to about 10 mm, or about 4 mm to about 10 mm,or about 0.5 mm to about 8 mm, or about 0.5 mm to about 6 mm.

In certain embodiments as otherwise described herein, the total amountof the aqueous suspension (e.g., of one or more of a rubber polymer anda plastic polymer), dispersant, coalescing aid, foaming surfactant,filler, pigment, and crosslinking agent is at least about 85 wt. % ofthe frothed composition. For example, in certain such embodiments, thetotal amount of the aqueous suspension (e.g., of one or more of a rubberpolymer and a plastic polymer), dispersant, coalescing aid, foamingsurfactant, filler, pigment, and crosslinking agent is at least about 90wt. %, or at least about 95 wt. %, or at least about 97.5 wt. %, or atleast about 99 wt. %, or at least about 99.5 wt. % of the frothedcomposition.

As described above, one aspect of the disclosure is a method forpreparing an acoustic panel comprising coating, directly onto theoutward major surface of a base structure, a frothed composition, dryingthe coated frothed composition, and curing the coated frothedcomposition.

The present inventors have determined that the coating layers asotherwise described herein, substantially scattering for light in thewavelength range 380-780 nm, is advantageously obscuring of the physicalfeatures of an underlying acoustic panel. The present inventors havefurther determined that, in certain embodiments as otherwise describedherein, inclusion of a pigment in the frothed composition as otherwisedescribed herein provides coating layers having a desired color, andaccordingly neither the outward major surface of the base structure ofthe base structure nor the exterior major surface of the coating layer.

In certain embodiments as otherwise described herein, the thickness ofthe coated frothed composition before drying is within the range ofabout 0.25 mm to about 25 mm. For example, in certain such embodiments,the thickness of the coated frothed composition before drying is withinthe range of about 0.25 mm to about 22.5 mm, or about 0.25 mm to about20 mm, or about 0.25 mm to about 17.5 mm, or about 0.25 mm to about 15mm, or about 0.25 mm to about 12.5 mm, or about 0.25 mm to about 10 mm,or about 0.25 mm to about 7.5 mm, or about 0.5 mm to about 25 mm, orabout 1 mm to about 25 mm, or about 1.5 mm to about 25 mm, or about 2 mmto about 25 mm, or about 2.5 mm to about 25 mm, or about 5 mm to about25 mm, or about 7.5 mm to about 25 mm, or about 10 mm to about 25 mm, orabout 12.5 mm to about 25 mm, or about 15 mm to about 25 mm, or about0.5 mm to about 20 mm, or about 0.5 mm to about 15 mm, or about 1 mm toabout 12.5 mm, or about 1 mm to about 10 mm.

The person of ordinary skill in the art will appreciate that the frothedcomposition can be coated directly onto the outward major surface of thebase structure using any of a variety of a coating means known in theart. For example, in certain embodiments as otherwise described herein,coating the frothed composition comprises coating the compositiondirectly onto the outward major surface of the base structure with aknife coater, roll coater, or a spray coater.

In certain embodiments as otherwise described herein, the coated frothedcomposition is dried at a temperature within the range of about 50° C.to about 350° C. For example, in certain such embodiments, the coatedfrothed composition is dried at a temperature within the range of about50° C. to about 300° C., or about 50° C. to about 250° C., or about 50°C. to about 200° C., or about 75° C. to about 350° C., or about 100° C.to about 350° C., or about 150° C. to about 350° C., or about 200° C. toabout 350° C., or about 75° C. to about 300° C., or about 100° C. toabout 250° C. A variety of apparatuses and methods can be used in thedrying, e.g., an infrared oven, or an oven without airflow.

In certain embodiments as otherwise described herein, the method furthercomprises roughening the exterior major surface of the coating layerafter drying the coated frothed composition. In certain embodiments ofthe methods as otherwise described herein, an exterior major surfacehaving a matte appearance can be provided by roughening the exteriormajor surface of the coating layer after drying the coated frothedcomposition by, for example, treating the exterior major surface with asolvent, or sanding the exterior major surface.

Notably, the methods described herein can be performed to provideacoustic panels particularly useful, for example, as acoustic ceilingtiles. Accordingly, another aspect of the disclosure is a ceiling systemcomprising a plurality of the acoustic panels described herein, oracoustic panels prepared according to a method described herein. Incertain embodiments, each panel of the plurality is oriented such thatthe exterior major surface of the coating layer is facing downwards. Theperson of ordinary skill in the art will appreciate that theperforations of the base structures of each panel will, in such anarrangement, be advantageously obscured by the coating layer while stillbeing accessible to air and sound waves.

EXAMPLES

The Examples that follow are illustrative of specific embodiments of theinvention, and various uses thereof. They are set forth for explanatorypurposes only, and are not to be taken as limiting the invention.

Example 1. Panel Preparation

A foamable mixture (Formulation 1) was prepared according to Table 1,below.

TABLE 1 Foamable Mixture Composition Component Amount (wet wt. %)Acrylic latex suspension (aqueous) 62 polycarboxylate sodium saltdispersant 3 texanol coalescing aid 3 sulphosuccinamine, sodium saltsurfactant 5 (aqueous) CaCO₃ 20 TiO₂ 8

The mixture was frothed using a wire whisk mixer for 6 minutes at 360rpm, and then for 15 minutes at 100 rpm, to provide a foam density ofabout 0.3 g/cm³. The foam was applied with a knife coater onto a ⅝-inchmineral wool base structure having a 3% total coverage of 1.4-mmperforations, and then dried at 200° C. for 2 minutes to provide acoating layer having a thickness of 1-2 mm.

Example 2. Foam Generation

Formulation 1 above was prepared using a continuous foam generator withgas injection and a 2-inch rotor-stator mixer. The foam was producedwith a rotor speed of approximately 1200 RPM with fluid pressure of 40PSI and gas back pressure of 60 PSI. The foam produced was similar instructure to the lab mixer results from Example 1 but with more uniformcell size.

Formulation 1 was prepared as described in Example 1 above but insteadof knife coating, the liquid foam was coated onto ceiling boards using areverse roll coater with substrate speed of 3.5 m/min, applicator rollat 3.0 m/min in the reverse direction and metering roll at 1 m/min inthe forward direction. The foam coating had a coating thickness between1 and 2 mm and had properties similar to the coating described above forknife coating.

Formulation 1 was prepared as described in Example 1 above but insteadof drying in a standard convection oven, was dried using a dryer whichdid not have any forced air convection and heated the sample only withinfrared radiation. The surface of the foam coating was heated for 2minutes and the surface temperature achieved at least 150° C. The driedcoating produced was similar in properties to those described in Example1.

Formulation 1 above was prepared using a continuous foam generator withgas injection and a 2-inch rotor-stator mixer. The foam was producedwith a rotor speed of approximately 1200 RPM with fluid pressure of 40PSI and gas back pressure of 60 PSI. The foam produced was similar instructure to the lab mixer results from Example 1 but with more uniformcell size.

Example 3. Acoustic Performance

A layer of foam of Formulation 2 was coated on a fiberglass substrate.Impedance tube measurements were taken of an uncoated fiberglasssubstrate and of a coated fiberglass substrate following the procedureof ASTM C384. The data are provided in FIG. 2 , and demonstrate that theacoustic absorption increases with the coating added. For example, at1000 Hz, the absorbance increases from 0.27 without foam coating to 0.43with foam coating—a relative change of 0.16.

Example 4. Additional Formulations

Additional formulations were prepared as described in Tables 2-3 below.Formulation 2 provided a foam with uniform aesthetic, although it wasless durable. Formulation 3 provided an acceptable foam.

TABLE 2 Formulation 2 Component Wet wt % Acrylic latex emulsion 68.6%Water 8.2% Acrylic polymer as rheology modifier 1.9% Sulphosuccinamide,sodium salt aqueous solution as 12.0% surfactant TiO₂ 9.3%

TABLE 3 Formulation 3 Component Wet wt % Acrylic latex emulsion 59.3%Carbodiimide as crosslinker 2.5% Water soluble polycarboxylate asdispersant 2.5% Texanol as coalescant 3.0% Sulphosuccinamide, sodiumsalt aqueous solution as 4.7% surfactant Calcium carbonate 20.1% TiO₂8.0%

Additional aspects of the disclosure are provided by the followingenumerated embodiments, which can be combined in any number or in anycombination that is not technically or logically inconsistent.

Embodiment 1. An Acoustic Panel Comprising

-   -   a base structure having one or more edges, an outward major        surface having a total area, and an inward major surface        opposing the outward major surface, the base structure having        independently a noise reduction coefficient of at least about        0.3; and    -   a coating layer directly disposed on the outward major surface        of the base structure, the coating layer being formed of an        open-cell foam, the coating layer having an exterior major        surface opposing the outward major surface of the base        structure,    -   wherein the coating layer is substantially scattering for light        in the wavelength range 380-780 nm, and has an absorption        coefficient of less than 0.5 for acoustic frequencies in the        range of 100 Hz to 10,000 Hz.

Embodiment 2. A panel according to embodiment 1, wherein the basestructure comprises

-   -   one or more of mineral wool, fiberglass, gypsum, wood fiber,        paper, cellulose    -   fiber, wet-laid felt, and foam;    -   one or more fillers; and    -   one or more binders;    -   present in the base structure in a combined amount of at least        about 85 wt. %, or at least about 95 wt. %, or at least about        97.5 wt. %, or at least about 99 wt. %.

Embodiment 3. A panel according to embodiment 2, wherein the basestructure comprises mineral wool.

Embodiment 4. A panel according to any of embodiments 1-3, wherein thebase structure comprises a plurality of perforations extending from theoutward major surface towards the inward major surface, the plurality ofperforations occupying an area of the outward major surface within therange of about 0.1% to about 10% of the total area of the outward majorsurface

Embodiment 5. A panel according to embodiment 4, wherein theperforations occupy an area of the outward major surface within therange of about 0.5% to about 10%, e.g., about 0.5% to about 8%, or about1% to about 6%.

Embodiment 6. A panel according to embodiment 4 or 5, wherein theperforations are annular, and the average diameter of the perforationsis within the range of about 0.25 mm to about 5 mm, e.g., about 0.25 mmto about 4 mm, or about 0.5 mm to about 3 mm.

Embodiment 7. A panel according to any of embodiments 4-6, wherein theaverage depth of the perforations is at least about 3 mm, e.g., at leastabout 4 mm, or at least about 5 mm.

Embodiment 8. A panel according to any of embodiments 1-7, wherein thebase structure has a thickness within the range of about 2 mm to about50 mm, e.g., about 2 mm to about 35 mm, or about 5 mm to about 25 mm.

Embodiment 9. A panel according to any of embodiments 1-8, wherein awidth of the panel is within the range of about 12 to about 60 inches,e.g., from 23 to 25 inches or from 46 to 50 inches, and a length of theacoustic panel is within the range of about 12 to about 144 inches,e.g., from 23 to 25 inches or from 46 to 50 inches.

Embodiment 10. A panel according to any of embodiments 1-9, wherein thebase structure has independently a noise reduction coefficient (NRC) ofat least about 0.5, e.g., at least about 0.6, or at least about 0.7, orat least about 0.8.

Embodiment 11. A panel according to any of embodiments 1-10, wherein thebase structure and the coating layer each independently have an airresistivity, and the air resistivity of the coating layer is equal to orless than the air resistivity of the base structure.

Embodiment 12. A panel according to embodiment 11, wherein the airresistivity of the coating layer is in a range of about 1 to about 2000kPa·s/m², or about 10 to about 1000 kPa·s/m², or about 100 to about 500kPa·s/m².

Embodiment 13. A panel according to any of embodiments 1-12, wherein thecoating layer has a light scattering percentage of at least about 50%(e.g., at least about 60%, or at least about 70%, or at least about 80%)for light in the wavelength region 380-780 nm.

Embodiment 14. A panel according to any of embodiments 1-13, having anNRC of at least about 0.3 (e.g., at least about 0.35, or at least about0.4, or at least about 0.45), or at least about 0.5 (e.g., at leastabout 0.6, or at least about 0.7, or at least about 0.8).

Embodiment 15. A panel according to any of embodiments 1-14, wherein theNRC of the panel is at least about 70% (e.g., at least about 80%, or atleast about 90%, or at least about 95%) of the NRC of the base structureindependently.

Embodiment 16. A panel according to any of embodiments 1-15, wherein thecoating layer has a thickness within the range of about 0.1 mm to about10 mm, e.g., about 0.1 mm to about 8 mm, or about 0.25 mm to about 6 mm.

Embodiment 17. A panel according to any of embodiments 1-16, wherein thecoating layer has an average cell diameter within the range of about 10μm to about 500 μm, e.g., about 25 μm to about 500 μm, or about 50 μm toabout 400 μm.

Embodiment 18. A panel according to any of embodiments 1-17, wherein thecoating layer has a density within the range of about 0.01 g/cm³ toabout 0.5 g/cm³, e.g., about 0.01 g/cm³ to about 0.35 g/cm³, or about0.05 g/cm³ to about 0.25 g/cm³.

Embodiment 19. A panel according to any of embodiments 1-18, wherein thecoating layer comprises

-   -   one or more foamable polymers (e.g., one or more of a rubber        polymer and a plastic polymer); and    -   one or more of a dispersant, a coalescing aid, and a foaming        surfactant;    -   present in the layer in a combined amount of at least about 30        wt. %, e.g., at least about 40 wt. %, or at least about 50 wt.        %, or at least about 60 wt. %, or at least about 70 wt. %.

Embodiment 20. A panel according to embodiment 19, wherein the plasticpolymer is an acrylic polymer.

Embodiment 21. A panel according to embodiment 19, wherein the rubberpolymer is a styrene butadiene copolymer.

Embodiment 22. A panel according to embodiment 19, wherein the foamablepolymer is a polyacrylate such as poly(methyl methacrylate), poly(ethylacrylate), poly(butyl acrylate), poly(acrylic acid), polystyrene, polyvinyl acetate or poly vinyl alcohol.

Embodiment 23. A panel according to embodiment 19, wherein the foamablepolymer is selected from polyurethanes, polyacrylates, styrene-acrylatecopolymers, styrene-ethylene-butadiene-styrene block copolymer (SEBS),poly(vinyl acetate) (PVAc), poly(ethylene-vinyl acetate) (EVA),ethylene-vinyl chloride copolymers.

Embodiment 24. A panel according to any of embodiments 19-23, whereinthe coating layer further comprises a filler.

Embodiment 25. A panel according to embodiment 24, wherein the filler iscalcium carbonate.

Embodiment 26. A panel according to embodiment 24 or 25, wherein thefiller is present in the coating layer in an amount within the range ofabout 1 wt. % to about 60 wt. %, e.g., about 10 wt. % to about 60%, orabout 15 wt. % to about 50 wt. %.

Embodiment 27. A panel according to any of embodiments 19-26, whereinthe coating layer further comprises a pigment.

Embodiment 28. A panel according to embodiment 27, wherein the pigmentis selected from titanium dioxide, zinc oxide, and carbon black.

Embodiment 29. A panel according to embodiment 27 or 28, wherein thepigment is present in the coating layer in an amount within the range ofabout 0.5 wt. % to about 20 wt. %, e.g., about 2.5 wt. % to about 15 wt.%.

Embodiment 30. A panel according to any of embodiments 19-29, whereinthe coating layer formed of an open-cell foam comprises

-   -   foamable polymer (e.g., acrylic polymer, styrene butadiene        polymer, or a mixture thereof), present in the coating layer in        an amount within the range of about 20 wt. % to about 80 wt. %,        e.g., about 25 wt. % to about 70 wt. %, or about 30 wt. % to        about 60 wt. %;    -   a dispersant, present in the coating layer in an amount within        the range of about 0.1 wt. % to about 10 wt. %, e.g., about 0.5        wt. % to about 8 wt. %;    -   a coalescing agent, present in the coating layer in an amount        within the range of about 0.1 wt. % to about 10 wt., e.g., about        0.5 wt. % to about 8 wt. %; and    -   a foaming surfactant, present in the coating layer in an amount        within the range of about 0.25 wt. % to about 15 wt. %, e.g.,        about 1 wt. % to about 12 wt. %.

Embodiment 31. A panel according to embodiment 30, wherein the coatinglayer further comprises

-   -   a filler, present in the foam in an amount within the range of        about 1 wt. % to about 60 wt. %, e.g., about 15 wt. % to about        45 wt. %; and    -   a pigment, present in the foam in an amount within the range of        about 0.5 wt. % to about 20 wt. %, e.g., about 2.5 wt. % to        about 15 wt. %.

Embodiment 32. A panel according to any of embodiments 1-31, wherein thecoating layer comprises a plurality of particles having an averageparticle size within the range of about 1 μm to about 50 μm (e.g., about1 μm to about 40 μm, or about 5 μm to about 30 μm) or about 0.1 mm toabout 10 mm (e.g., about 0.1 mm to about 8 mm, or about 0.5 mm to about6 mm).

Embodiment 33. A panel according to any of embodiments 19-32, whereinthe total amount of the foamable polymer, dispersant, coalescing aid,foaming surfactant, filler, pigment, and crosslinking agent is at leastabout 85 wt. % (e.g., at least about 90 wt. %, or at least about 95 wt.%, or at least about 97.5 wt. %, or at least about 99 wt. %) of thecoating layer.

Embodiment 34. A panel according to embodiment 33, wherein the color ofthe exterior major surface is white or black.

Embodiment 35. A panel according to any of embodiments 1-34, wherein theexterior major surface of the coating layer has a gloss of less thanabout 20 gloss units (GU), e.g. less than about 15 GU, or less thanabout 10 GU.

Embodiment 36. A panel according to any of embodiments 1-36, wherein thepanel is resistant to sagging.

Embodiment 37. A method for preparing an acoustic panel according to anyof embodiments 1-36, comprising

-   -   providing a base structure having one or more edges, an outward        major surface having a total area, and an inward major surface        opposing the outward major surface, the base structure having        independently an NRC of at least about 0.3;    -   coating, directly onto the outward major surface, a frothed        composition comprising an aqueous suspension of one or more        foamable polymers (e.g., one or more of a rubber polymer and a        plastic polymer), and one or more of a dispersant, a coalescing        aid, and a foaming surfactant, present in the composition in a        combined amount of at least about 50%, e.g., at least about 60%,        or at least about 70%, or at least about 80%, or at least about        90%; and    -   drying the coated frothed composition to provide a coating layer        formed of an open-cell foam, the coating layer having an        exterior major surface opposing the outward major surface of the        base structure.

Embodiment 38. A method according to embodiment 37, wherein the basestructure comprises a plurality of perforations extending from theoutward major surface towards the inward major surface, the plurality ofperforations occupying an area of the outward major surface within therange of about 0.1% to about 10% of the total area of the outward majorsurface.

Embodiment 39. A method according to embodiment 37 or 38, wherein thefrothed composition has a density within the range of about 0.01 g/cm³to about 0.5 g/cm³, e.g., about 0.01 g/cm³ to about 0.35 g/cm³, or about0.05 g/cm³ to about 0.25 g/cm³.

Embodiment 40. A method according to any of embodiments 37-39, whereinthe rubber polymer is a styrene butadiene copolymer.

Embodiment 41. A method according to any of embodiments 37-39, whereinthe plastic polymer is an acrylic polymer.

Embodiment 42. A method according to any of embodiments 37-39, whereinthe foamable polymer is a polyacrylate such as poly(methylmethacrylate), poly(ethyl acrylate), poly(butyl acrylate), poly(acrylicacid), polystyrene, poly vinyl acetate or poly vinyl alcohol.

Embodiment 43. A method according to any of embodiments 37-39, whereinthe foamable polymer is selected from polyurethanes, polyacrylates,styrene-acrylate copolymers, styrene-ethylene-butadiene-styrene blockcopolymer (SEBS), poly(vinyl acetate) (PVAc), poly(ethylene-vinylacetate) (EVA), ethylene-vinyl chloride copolymers.

Embodiment 44. A method according to any of embodiments 37-43, whereinthe frothed composition further comprises a filler.

Embodiment 45. A method according to embodiment 44, wherein the filleris calcium carbonate.

Embodiment 46. A method according to embodiment 44 or 45, wherein thefiller is present in the frothed composition in an amount within therange of about 5 wt. % to about 50 wt. %, e.g., about 10 wt. % to about40%, or about 15 wt. % to about 30 wt. %.

Embodiment 47. A method according to any of embodiments 37-46, whereinthe frothed composition further comprises a pigment.

Embodiment 48. A method according to embodiment 46 wherein the pigmentis selected from titanium dioxide, zinc oxide, and carbon black.

Embodiment 49. A method according to embodiment 46 or 47, wherein thepigment is present in the frothed composition in an amount within therange of about 0.5 wt. % to about 20 wt. %, e.g., about 2.5 wt. % toabout 15 wt. %.

Embodiment 50. A method according to any of embodiments 36-49, whereinthe frothed composition comprises a plurality of particles having anaverage particle size within the range of about 1 μm to about 50 μm(e.g., about 1 μm to about 40 μm, or about 5 μm to about 30 μm) or about0.1 mm to about 10 mm (e.g., about 0.1 mm to about 8 mm, or about 0.5 mmto about 6 mm).

Embodiment 51. A method according to any of embodiments 37-50, whereinthe total amount of the aqueous suspension of one or more of a rubberpolymer and a plastic polymer, dispersant, coalescing aid, foamingsurfactant, filler, pigment, and crosslinking agent is at least about 85wt. % (e.g., at least about 90 wt. %, or at least about 95 wt. %, or atleast about 97.5 wt. %, or at least about 99 wt. %) of the frothedcomposition.

Embodiment 52. A method according to any of embodiments 37-51, whereinthe thickness of the coated frothed composition before drying is withinthe range of about 0.25 mm to about 25 mm, e.g., about 0.25 mm to about20 mm, or about 0.5 mm to about 15 mm.

Embodiment 53. A method according to any of embodiments 37-52, whereincoating the frothed composition comprises applying the composition tothe outward major surface of the base structure with a knife coater,roll coater, or a spray coater.

Embodiment 54. A method according to any of embodiments 37-53, whereinthe drying temperature is within the range of about 50° C. to about 350°C., e.g., about 50° C. to about 300° C., or about 100° C. to about 250°C.

Embodiment 55. A method according to any of embodiments 37-54, furthercomprising roughening the exterior major surface of the coating layerafter drying the coated frothed composition.

Embodiment 56. An acoustic panel according to any of embodiments 1-36,made by a method of any of embodiments 37-55.

Embodiment 57. A panel system comprising:

-   -   a plurality of support beams arranged in a support grid so as to        form a plurality of grid openings in the support grid; and    -   a plurality of panels respectively aligned with the openings of        the support grid, the plurality of panels including a first        acoustic panel according to any of embodiments 1-36 or 56,        wherein the first acoustic panel is oriented such that the        exterior major surface of the facing layer is facing an interior        space adjacent to the support grid.

Embodiment 58. The panel system according to embodiment 57, wherein thepanel system is a ceiling system and the support grid is a ceiling grid.

Embodiment 59. The panel system according embodiment 57 or embodiment58, wherein each of the plurality of panels is an acoustic panelaccording to any of embodiments 1-36 or 56.

What is claimed is:
 1. An acoustic panel comprising a base structurehaving one or more edges, an outward major surface having a total area,and an inward major surface opposing the outward major surface; and acoating layer directly disposed on the outward major surface of the basestructure, the coating layer being formed of an open-cell foam, thecoating layer having an exterior major surface opposing the outwardmajor surface of the base structure, the coating layer comprising one ormore foamable polymers, present in the coating layer in an amount withinthe range of about 20 wt. % to about 80 wt. %; a dispersant, present inthe coating layer in an amount within the range of about 0.1 wt. % toabout 10 wt. %; a coalescing agent, present in the coating layer in anamount within the range of about 0.1 wt. % to about 10 wt. % and afoaming surfactant, present in the coating layer in an amount within therange of about 0.25 wt. % to about 15 wt. %.
 2. The acoustic panelaccording to claim 1, wherein the coating layer is substantiallyscattering for light in the wavelength range 380-780 nm, and has anabsorption coefficient of less than 0.5 for acoustic frequencies in therange of 100 Hz to 10,000 Hz.
 3. The acoustic panel according to claim1, wherein the coating layer has a light scattering percentage of atleast about 80% for light in the wavelength region 380-780 nm.
 4. Theacoustic panel according to claim 1, wherein the coating layer has athickness within the range of about 0.1 mm to about 10 mm.
 5. Theacoustic panel according to claim 1, wherein the coating layer has anaverage cell diameter within the range of about 10 μm to about 500 μmand a density within the range of about 0.01 g/cm³ to about 0.5 g/cm³.6. The acoustic panel according to claim 1, wherein the one or morefoamable polymers include one or more of polyurethanes, polyacrylates,styrene-acrylate copolymers, styrene-butadiene copolylmers,styrene-ethylene-butadiene-styrene block copolymer (SEBS), poly(vinylacetate) (PVAc), poly(ethylene-vinyl acetate) (EVA), ethylene-vinylchloride copolymers, polystyrene, and polyvinyl alcohol.
 7. The acousticpanel according to claim 1, wherein the one or more foamable polymersinclude a polyacrylate.
 8. The acoustic panel according to claim 1,wherein the coating layer further comprises a filler, present in thecoating layer in an amount within the range of about 1 wt. % to about 60wt. %.
 9. The acoustic panel according to claim 1, wherein the coatinglayer further comprises a pigment, present in the coating layer in anamount within the range of about 0.5 wt. % to about 20 wt. %.
 10. Theacoustic panel according to claim 1, wherein the exterior major surfaceof the coating layer has a gloss of less than about 20 gloss units (GU).11. The acoustic panel according to claim 1, wherein the base structurecomprises one or more of mineral wool, fiberglass, gypsum, wood fiber,paper, cellulose fiber, wet-laid felt, and foam; one or more fillers;and one or more binders; present in the base structure in a combinedamount of at least about 85 wt. %.
 12. The acoustic panel according toclaim 1, wherein the base structure comprises a plurality ofperforations extending from the outward major surface towards the inwardmajor surface, the plurality of perforations occupying an area of theoutward major surface within the range of about 0.1% to about 10% of thetotal area of the outward major surface.
 13. The acoustic panelaccording to claim 1, wherein the base structure has independently anNRC of at least about 0.3.
 14. The acoustic panel according to claim 1,having an NRC of at least about 0.3, e.g., at least about 0.5.
 15. Theacoustic panel according to claim 1, wherein the NRC of the panel is atleast about 70% of the independent NRC of the base structure.
 16. Theacoustic panel according to claim 1, the coating layer has an absorptioncoefficient of less than 0.3 for acoustic frequencies in the range of100 Hz to 10,000 Hz.
 17. The acoustic panel according to claim 1,wherein the base structure has an air resistivity that is at least 50%greater than an air resistivity of the coating layer.
 18. The acousticpanel according to claim 1, wherein the base structure and the coatinglayer each independently have an air resistivity, and the airresistivity of the coating layer is equal to or less than the airresistivity of the base structure, and, wherein the air resistivity ofthe coating layer is in a range of about 1 to about 2000 kPa·s/m².
 19. Amethod for preparing an acoustic panel according to claim 1, comprisingproviding a base structure having one or more edges, an outward majorsurface having a total area, and an inward major surface opposing theoutward major surface; coating, directly onto the outward major surface,a frothed composition comprising an aqueous suspension of one or morefoamable polymers, and a dispersant, a coalescing aid, and a foamingsurfactant; and drying the coated frothed composition to provide thecoating layer formed of an open-cell foam, the coating layer having anexterior major surface opposing the outward major surface of the basestructure.
 20. A panel system comprising: a plurality of support beamsarranged in a support grid so as to form a plurality of grid openings inthe support grid; and a plurality of panels respectively aligned withthe openings of the support grid, the plurality of panels including afirst acoustic panel according to claim 1, wherein the first acousticpanel is oriented such that the exterior major surface of the facinglayer is facing an interior space adjacent to the support grid.
 21. Anacoustic panel according to claim 1, wherein the one or more foamablepolymers comprise an acrylic polymer, a styrene butadiene polymer, or amixture thereof.